The present invention relates to a method of banding groups of sheets, in particular banknotes.
The invention finds application to advantage in machines by which banknotes are ordered into groups and transferred to a strapper/bander by which at least one band is looped around each single group of notes and made secure.
It is well known that banks need to move notable amounts of paper money around on a daily basis, whether central banks by which new banknotes are issued, or trading banks through which the notes are circulated. To this end, banknotes are first sorted into groups and then placed for the purposes of transportation into relative bags or cassettes.
To ensure they can be ordered and transported without the risk of breaking up and to prevent their being tampered with, the groups are secured with bands serving to keep the notes together and minimize opportunities for robbery or pilfering.
Generally speaking, banknotes are fed singly and in succession into machines of the aforesaid type and, having been examined and sorted according to denomination and/or type, are directed separately toward the outlets of respective channels along which the groups are formed.
In this way stacks of single banknotes are formed at each of the outlets, and as the single notes are accumulated and ordered in predetermined numbers, each stack is taken up and transferred to a station at which it will be suitably strapped or banded.
Alternatively, still with machines of the type in question, notes that have been checked and sorted beforehand can be fed into the formation channels already bundled and strapped or banded, so that the stacks which form at the outlet of each channel are stacks of bundles rather than of single notes, and these same stacks of bundles are taken up similarly and transferred to the aforementioned strapping or banding station.
For the reasons mentioned above, the strapping or banding operation must be fast and accurate and ensure an end product characterized by strength and quality. In the case of central banks, especially, newly printed notes must be handled with extreme care in order to avoid any accidental damage that might prevent their being issued.
The prior art embraces machines for strapping and banding banknotes comprising a feed unit by means of which a continuous strip of material decoiling from a respective roll is cast toward a gripper and placer device that moves along a path following the periphery of the group of notes, offering the strip to one side of the group after another and keeping the material tensioned against the notes until the point of engaging further devices which secure and cut the strip, thus bringing the strapping/banding operation to completion.
It will be evident that the solution of utilizing an active mechanism to place and tension the strip around the stack of notes is liable to prejudice a correct execution of the wrapping step, especially at the edges of the stack, where an incorrectly controlled tension can have the effect of damaging and/or displacing the notes, should the strip be overtensioned, or on the other hand of rendering the strapping or banding action ineffective if the strip is too slack.
The method in question has been found especially unsuitable, especially with regard to correct and uniform tensioning of the strip, when adopted for strapping or banding notably thick or tall stacks consisting in a number of notes greater than that of a standard bundle, or in a plurality of bundles stacked together.
Another drawback of such machines is encountered during the operation of making the strip secure, accomplished generally by overlapping the ends and sealing them together. The tensioned state of the strip tends to render the operation difficult.
Accordingly, and for the reasons outlined above, machines of the type in question are limited in terms of operating capacity, lacking in precision and not altogether reliable.
The object of the present invention is to provide a machine for banding groups of sheets, banknotes in particular, such as will apply the bands swiftly and accurately and produce an end result assuring strength and quality.
A further object of the invention is to provide a machine capable of strapping or banding groups of single banknotes and groups of bundled banknotes with equal ease.
The stated object is realized according to the present invention in a method for securing at least one band of strip material around a substantially parallelepiped block of sheets, in particular banknotes, which comprises the steps of causing at least one continuous strip decoiling from a roll to advance along a first predetermined path through the agency of first feed means; restraining one end of the continuous strip through the agency of gripping means designed to interact with a leading portion of the strip that coincides with a first end of the band; causing the block of sheets, through the agency of second feed means, to advance along a second path transversely to the first path in such a way as to enter into contact with the strip and, continuing to advance along the second path, cause the strip to decoil further from the roll and bend to a xe2x80x9cUxe2x80x9d profile; engaging the leading portion of the strip through the agency of bending means and flattening it against a face of the block positioned rearwardmost relative to the direction followed along the second path; drawing the strip into overlapping contact with the first end of the band, through the agency of diverter means located on the side of the second path opposite to the bending means; cutting the strip at the overlap through the agency of cutter means, to define a second end of the band; securing the second end of the band to the first end through the agency of sealing means.
The stated object is realized similarly according to the invention in a machine for securing at least one band of strip material around a substantially parallelepiped block of sheets, in particular banknotes, comprising first feed means by which at least one continuous strip decoiling from a roll is caused to advance along a first predetermined path; a channel serving to guide the block of sheets and establishing a second predetermined path transverse to the first path; gripping means positioned externally of the channel and in such a way as to interact with a leading portion of the continuous strip and restrain one end of the selfsame strip; second feed means by which a block of sheets is made to advance along the channel and enter into contact with the strip; bending means operating in conjunction with the gripping means, by which the leading portion of the strip is flattened against a face of the block positioned rearwardmost relative to a direction followed along the second path; diverter means located on the side of the channel opposite to the bending means, by which the strip is engaged and drawn into overlapping contact with at least a part of the leading portion; cutter means by which the strip is severed at the overlap to define a second end of the band; sealing means by which the second end of the band is secured to the first end.